Automotive lamp
AssigneeKoito Manufacturing Co., Ltd.
InventorsTomoyuki Ichikawa, Satoshi Kikuchi, Ryosuke Matsuhana
Life of this patent
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Abstract
A lighting circuit turns on multiple semiconductor light sources. Multiple current sources are each coupled in series with a corresponding one from among the semiconductor light sources. A switching converter supplies a driving voltage VOUT across each of multiple series connection circuits formed of the multiple semiconductor light sources and the multiple current sources. A converter controller controls a switching transistor of the switching converter based on a relation between a voltage across one from among the multiple current sources and a reference voltage having a positive correlation with the temperature Tj.
Claims4
A lighting circuit structured to turn on and off a plurality of semiconductor light sources, the lighting circuit comprising:
- a plurality of current sources each of which is to be coupled in series with a corresponding one from among the plurality of semiconductor light sources;
- a switching converter structured to supply a driving voltage across both ends of each of a plurality of series connection circuits configured of the plurality of semiconductor light sources and the plurality of current sources;
- and
- a converter controller structured to control the switching converter based on a relation between a voltage across both ends of one from among the plurality of current sources and a reference voltage having a positive correlation with temperature, wherein the protection circuit comprises:
- an abnormal state detection circuit structured to assert an abnormal state detection signal when an abnormal state has been detected;
- and
- a data replacement circuit structured such that, when the abnormal state detection signal is negated, the data replacement circuit outputs the plurality of individual control signals as they are, and such that, when the abnormal state detection signal is asserted, the data replacement circuit outputs a set of predetermined values.
Dependencies are inferred from the claim text.